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Thread: Manifold Gauge and Hose question
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21-05-2009, 06:35 PM #1
Manifold Gauge and Hose question
Hi all,
Just a quick question about gauges and hoses really,
I work mainly on package units with the basic schrader valves (without service valves).
Now I have just carried out my 2079 I am now required to test all the units for leaks every 6 months, I would like to carry out this by measuring and recording the superheat/subcooling, but every time I engage my hoses I am probably doing more harm than good!
Now I am just wondering if there are any hoses out there that are specially designed to be put on and off these valves without loss of refigerant, for example with a longer end connection so it screws on far enough before it releases the valve so its sealed before releasing the refigerant.
I currently use a red hose with a tap on the end and before attempting to take the hose off I close the tap and open my hi and low valve to rid whats left in the hose before removing.
Any advice or help would be brilliant,
Thanks Lee
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21-05-2009, 07:34 PM #2
Re: Manifold Gauge and Hose question
Hi Lees,
http://www.srw.co.uk/ do a set of hoses fitted with non return valves that`ll hold the refrigerant the line. Of course that means you`ll have to have a diferent manifold for each gas you deal with but that`s no bad thing as you`ll not have to purge the hoses each time you connect them.
You`ll need to register with srw to view them but they do lots more stuff at good prices.
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21-05-2009, 09:33 PM #3
Re: Manifold Gauge and Hose question
Yes, you probably are.
You would be better off tracking evap delta-T. An increase in dT indicates airflow problems, while a decrease indicates refrigerant flow problems... or high humidity... or various other problems.
If these are heat pumps, you would want to track the dT of the indoor coil in each mode, as the temp and volume of indoor airflow is relatively constant.
Of course you would first need to establish a base dT for each unit in each mode (with everything functioning properly) to compare to.Last edited by Gary; 21-05-2009 at 09:50 PM.
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21-05-2009, 09:59 PM #4
Re: Manifold Gauge and Hose question
I see no sense at all in periodically testing for refrigerant charge problems. Why not instead periodically test for any and all problems?
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22-05-2009, 07:47 AM #5
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22-05-2009, 05:21 PM #6
Re: Manifold Gauge and Hose question
IMO gauges should only be connected to systems as a last resort, not on a maintenance/ leak check visit.
As Gary says there are many ways to check if the system has a leak, firstly by carrying out a visual check of the system paying close attention to any signs of oil around joints, schraeders etc and maybe even using your leak sniffer.
Other checks that need performing are,to verify the airflow through condenosr/evap are clear and are not full of dirt by checking the Delt T (air on/air off).The difference between genius and stupidity is that genius has its limits.
Marc
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22-05-2009, 05:49 PM #7
Re: Manifold Gauge and Hose question
i am currently doing a nvq level 2 in ac and refigeration. i asked my tutor the other day about putting gauges on a system for maintenace. he said it is illegal to do so. you only put them on if you think the system is short of gas and as a last procedure really.
is this true what he is telling me?
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22-05-2009, 05:56 PM #8
Re: Manifold Gauge and Hose question
I don't think it is illegal but too many engineers think the first thing that should be done is put the gauges on when it isn't.
Firstly it should be to check correct water/airflow through both coils, take temperatures and then if there is still a problem i would connect my gauges to check subcooling and then superheat.The difference between genius and stupidity is that genius has its limits.
Marc
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22-05-2009, 11:12 PM #9
Re: Manifold Gauge and Hose question
I always remember being told that gauges are diagnostic tool not maintenence tool.
Nuff Said.
"I'm anaspeptic, frasmotic, even compunctuous to have caused you such pericombobulation."
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22-05-2009, 11:41 PM #10
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23-05-2009, 01:34 AM #11
Re: Manifold Gauge and Hose question
If it is not, it should be!
Oh dear... will a logo have to change?
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23-05-2009, 11:44 AM #12
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23-05-2009, 12:34 PM #13
Re: Manifold Gauge and Hose question
If the condenser coil is accessible, measure the temperature at the end of the coil, work your way down from the top and you should see a decrease in temperature, when you start to see no change in temperature that reading will be your saturated condensing temperature, subtract the liquid line temperature and you will have the subcooling value.
CheersTutto il Mondo e un Paese
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23-05-2009, 03:34 PM #14
Re: Manifold Gauge and Hose question
You only have to check your system for leaks according to EN378, and it's not illegal to put your gauges on a system.
Why not use these
I have 2 (1/4" and 5/16 " SAE) in each toolcase, it's a standard tool I use since years.It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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26-05-2009, 11:56 AM #15
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26-05-2009, 11:58 AM #16
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26-05-2009, 09:17 PM #17
Re: Manifold Gauge and Hose question
I used the subcooling example as it would be very rare on AC systems to have access to the evaporator coil, because you are looking for the end of the latent heat gain the same principle would apply for superheat, on Daikin splits for example you can see the coil sensor values via the controller (setting code 41).
Gary makes a great point regarding checking air/water flow prior to anything, I have been caught out several times, especially on water chillers in the past.
CheersTutto il Mondo e un Paese
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26-05-2009, 09:39 PM #18
Re: Manifold Gauge and Hose question
your location is manchester you have dean and wood +ryan aircon ref spares on your doorstep
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26-05-2009, 09:47 PM #19
Re: Manifold Gauge and Hose question
I heard Ryan Air Con Spares had moved/closed and was concentrating on internet orders instead?
The difference between genius and stupidity is that genius has its limits.
Marc
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04-06-2009, 10:58 AM #20
Re: Manifold Gauge and Hose question
check with heatcraft,,,,australia there have some fittings u cn use on the schrader valve ...
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10-06-2009, 10:51 PM #21
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